Bone Turns Orange And Auto IK Doesn't Work
I've stumbled upon this question myself and believe that this is an issues regarding X-Axis mirror and Auto-IK working together.
To reproduce the issue,

In pose mode, turn X-Axis mirror and Auto-IK on together.
Move a bone that is properly mirrored, the Auto-IK and X-Axis mirror should work fine, result in the mirrored bone moving accordingly.
Turn off X-Axis mirror, then try moving another bone, the &quot;mirrored&quot; bone you just moved (the one you didn't directly grab) will appear orange and attempt to stay in its place, result in certain bones locked down.


So to clear this situation, you can simply &quot;turn X-Axis mirror and Auto-IK on together again&quot; and &quot;move a bone that is NOT properly mirrored (like the head or any other bone in the center).&quot; Then you should be safe to turn your X-Axis mirror option off!